1. Field
Embodiments relate to the management of extents for space efficient storage volumes by reusing previously allocated extents.
2. Background
A storage controller may be coupled to one or more of a plurality of hosts. The storage controller may manage a plurality of storage devices, such as disk drives, tape drives, etc., that are coupled to the storage controller. The plurality of hosts may access data stored in the storage devices via the storage controller.
The storage volumes stored in the storage devices may be maintained as space efficient storage volumes. In space efficient storage volumes, the storage volumes may be thinly provisioned which means that physical storage space is not allocated to the storage volumes until a write to the storage volumes requires the space. The amount of space that is allocated is based on the amount of data that is written to the storage volumes. In space efficient storage volumes, the logical space defined for the storage volumes exceeds the physical space allocated to the storage volumes.
In space efficient storage volumes, the space for the storage volumes are allocated when the write operations actually write tracks, extents, blocks, or other storage units to the storage volumes. If the unit for storing data is an extent, then the space efficient storage volumes are referred to as extent space efficient storage volumes.